Surge arresters are used in the electrical power industry for protecting expensive pieces of electrical equipment by limiting the magnitude of surges in voltage. Such surges in voltage often occur, for example, when lightning strikes. When this happens, the surge arrester shunts the surge to the ground, thereby protecting the piece of electrical equipment and the circuit from damage or destruction.
Typically, present day surge arresters commonly include an elongated, hollow cylindrical weathershed housing made of an insulating material such as porcelain or a polymer, a plurality of non-linear resistive blocks stacked within the housing and a conductive member at each end to form a pair of end terminals. The non-linear resistive blocks commonly contain silicone carbide (SiC) or zinc oxide (ZnO), which are usually shaped as relatively short cylinders. These non-linear resistive blocks are stacked end to end within the arrester housing, and held under axial compression between the end terminals. The number of blocks employed is a function of the material (SiC or ZnO) as well as the voltage rating for the assembly. Thus, a surge arrester with a high voltage rating would be longer than a surge arrester with a low voltage rating.
Surge arresters with high voltage ratings are often used to protect outdoor equipment. These high voltage surge arresters are typically base mounted in either a horizontal or vertical position and subjected to cantilever mechanical loads. In particular, these surge arresters are often subjected to severe dynamic mechanical loads caused by various conditions such as high winds, snow, icing, earthquakes, line breakage, etc. Consequently, these surge arresters must be constructed to withstand such extreme mechanical loads. Accordingly, as the application voltage increases, the length of the arrester increases requiring high cantilever strength to withstand the mechanical loads applied thereto by the environment.
Examples of some prior surge arresters are disclosed in Bolton et al U.S. Pat. No. 3,172,073; Ferree U.S. Pat. No. 3,447,118; Bergh et al U.S. Pat. No. 4,467,387; Ozawa et al U.S. Pat. No. 4,814,936; Doone et al U.S. Pat. No. 4,851,955; and Raudabaugh U.S. Pat. No. 4,899,248.
In view of the above, it is apparent that a need exists to provide an electrical assembly which increases the mechanical strength of a surge arrester, especially surge arresters with a high voltage rating. This invention addresses this need in the art along with other needs which will become apparent to those skilled in the art once given this disclosure.